<?php
/**
 * 实例化model类
 * @param string $table
 * @return \app\model\Model
 */
function model($table = ''){
    return new \app\model\Model($table);
}

/**
 * authcode加密函数
 * @param unknown $string
 * @param string $key
 * @param string $operation
 * @param number $expiry
 * @return string
 */
function authcode($string, $key, $operation = false, $expiry = 0){
    $ckey_length = 4;
    $key = md5($key ? $key : 'ABCDEFGabcdefg1234567');
    $keya = md5(substr($key, 0, 16));
    $keyb = md5(substr($key, 16, 16));
    $keyc = $ckey_length ? ($operation? substr($string, 0, $ckey_length):substr(md5(microtime()), -$ckey_length)) : '';
    $cryptkey = $keya.md5($keya.$keyc);
    $key_length = strlen($cryptkey);
    $string = $operation? base64_decode(substr($string, $ckey_length)) :
    sprintf('%010d', $expiry ? $expiry + time() : 0).substr(md5($string.$keyb), 0, 16).$string;
    $string_length = strlen($string);
    $result = '';
    $box = range(0, 255);
    $rndkey = array();
    for($i = 0; $i <= 255; $i++) {
        $rndkey[$i] = ord($cryptkey[$i % $key_length]);
    }
    for($j = $i = 0; $i < 256; $i++) {
        $j = ($j + $box[$i] + $rndkey[$i]) % 256;
        $tmp = $box[$i];
        $box[$i] = $box[$j];
        $box[$j] = $tmp;
    }
    for($a = $j = $i = 0; $i < $string_length; $i++) {
        $a = ($a + 1) % 256;
        $j = ($j + $box[$a]) % 256;
        $tmp = $box[$a];
        $box[$a] = $box[$j];
        $box[$j] = $tmp;
        $result .= chr(ord($string[$i]) ^ ($box[($box[$a] + $box[$j]) % 256]));
    }
    if($operation) {
        if((substr($result, 0, 10) == 0 || substr($result, 0, 10) - time() > 0) &&
            substr($result, 10, 16) == substr(md5(substr($result, 26).$keyb), 0, 16)) {
                return substr($result, 26);
            } else {
                return '';
            }
    } else {
        return $keyc.str_replace('=', '', base64_encode($result));
    }
}

/**
 * 加密
 * @param array $data
 * @param string $key
 * @param number $expiry
 * @return string
 */
function encrypt(array $data, $key = 'wyc', $expiry = 0){
    return authcode(json_encode($data), $key, false, $expiry);
}

/**
 * 解密
 * @param string $data
 * @param string $key
 * @return mixed
 */
function decrypt(string $data, $key = 'wyc'){
    $decrypt = authcode($data, $key, true);
    if (!empty($decrypt)) return json_decode($decrypt, true);
}

/**
 * 格式化成功返回数据
 * @param array $data
 * @return number[]|unknown[]|string[]
 */
function success(array $data):array
{
    return [
        'code' => $data['code'] ?? 0,
        'msg' => $data['msg'] ?? '操作成功',
        'data' => $data['data'] ?? ''
    ];    
}

/**
 * 格式化失败返回数据
 * @param array $data
 * @return array
 */
function error(array $data):array
{
    return [
        'code' => $data['code'] ?? -1,
        'msg' => $data['msg'] ?? '操作失败'
    ]; 
}

